Dental Caries in the Elderly

Studies in the United States and other countries have shown that there is continued caries activity with advancing age. These studies, however, do not elaborate on the nature of the dental caries nor its anatomical location on the tooth. It has been assumed that dental caries occur on the coronal portion of retained teeth and that recurrent decay around existing restorations represents the major form of the disease. In addition to continued coronal caries activity in adults, the problem of carious lesions occurring on the exposed roots of teeth has been identified in a number of recent surveys. The exposure of the root surface to the oral cavity is a consequence of the apical migration of the periodontal attachment through periodontal disease and dental treatment which renders this part of the tooth at risk of the dental caries process. However, there are several distinct differences between coronal and root caries. The continued occurrence of coronal caries in adults and the projected increase m the prevalence of root caries suggests an expanded role for the restorative and preventive services for the older adult patient. Although the techniques relating to coronal caries are well-established, those relating to root caries are just beginning to be explored and developed. Many of the principles, materials and philosophies which have proved to be effective for coronal caries are not equally efficacious when the tooth root is involved. This area represents a fertile field for research and development in the older adult patient.     

口泰含漱液对控制菌斑和牙龈炎的疗效分析

本研究采用双盲随机对照法观察口泰含液对牙龈炎及控制菌斑的疗效。结果显示：实验组的牙龈指数,龈沟出血指数及菌斑指数以在含漱５天后均有明显的改善,且与对照组的比较也有明显的差异。     

Thermal Inactivation of Bacillus anthracis Spores in Cow's Milk

Decimal reduction time (time to inactivate 90% of the population) (D) values of Bacillus anthracis spores in milk ranged from 3.4 to 16.7 h at 72°C and from 1.6 to 3.3 s at 112°C. The calculated increase of temperature needed to reduce the D value by 90% varied from 8.7 to 11.0°C, and the Arrhenius activation energies ranged from 227.4 to 291.3 kJ/mol. Six-log-unit viability reductions were achieved at 120°C for 16 s. These results suggest that a thermal process similar to commercial ultrahigh-temperature pasteurization could inactivate B. anthracis spores in milk.     

Lactobacilli Isolation from Dental Plaque and Saliva of a Group of Patients with Caries and Characterization of their Surface Properties

The oral cavity is a complex ecosystem colonized by micro-organisms which play different roles. The aims of this study were to identify Lactobacillus strains from the teeth and saliva of children lacking in dental care and to study the surface characteristics related to the adhesion capability of these micro-organisms. The population considered is from Tucumán, Argentina. It is characterized by a dmfs index over 5 and an absence of dental care. Lactobacilli were isolated and identified by microscopic observations, biochemical tests and modified API CH 50. Bacterial surface studies included: hydrophobicity, acid and basic characteristics, blood cell agglutination and salt aggregation. Thirty strains were isolated. The major group was facultative heterofermentative. The surface characteristic studies did not indicate that lactobacilli are hydrophobic, neither do they show high basic nor acid charges. Lactobacilli isolated from saliva auto-agglutinated and also agglutinated ABO red blood cells. Salt aggregation was not a characteristic property. In this preliminary work, lactobacilli from teeth and saliva from this specific population were not demonstrated to have relevant adhesion properties.     

Zinc and Metallothionein in the Development and Progression of Dental Caries

Biological Trace Element Research - Chronic oxidative stress and reactive oxygen species (ROS) in oral cavity as well as acidic pH on dental enamel surface due to the metabolic activities of...     

Urease and Dental Plaque Microbial Profiles in Children

Objective

Urease enzymes produced by oral bacteria generate ammonia, which can have a significant impact on the oral ecology and, consequently, on oral health. To evaluate the relationship of urease with dental plaque microbial profiles in children as it relates to dental caries, and to identify the main contributors to this activity.

Methods

82 supragingival plaque samples were collected from 44 children at baseline and one year later, as part of a longitudinal study on urease and caries in children. DNA was extracted; the V3–V5 region of the 16S rRNA gene was amplified and sequenced using 454 pyrosequencing. Urease activity was measured using a spectrophotometric assay. Data were analyzed with Qiime.

Results

Plaque urease activity was significantly associated with the composition of the microbial communities of the dental plaque (Baseline P = 0.027, One Year P = 0.012). The bacterial taxa whose proportion in dental plaque exhibited significant variation by plaque urease levels in both visits were the family Pasteurellaceae (Baseline P<0.001; One Year P = 0.0148), especially Haemophilus parainfluenzae. No association was observed between these bacteria and dental caries. Bacteria in the genus Leptotrichia were negatively associated with urease and positively associated with dental caries (Bonferroni P<0.001).

Conclusions

Alkali production by urease enzymes primarily from species in the family Pasteurellaceae can be an important ecological determinant in children’s dental plaque. Further studies are needed to establish the role of urease-associated bacteria in the acid/base homeostasis of the dental plaque, and in the development and prediction of dental caries in children.     

The Dental Plaque Microbiome in Health and Disease

Dental decay is one of the most prevalent chronic diseases worldwide. A variety of factors, including microbial, genetic, immunological, behavioral and environmental, interact to contribute to dental caries onset and development. Previous studies focused on the microbial basis for dental caries have identified species associated with both dental health and disease. The purpose of the current study was to improve our knowledge of the microbial species involved in dental caries and health by performing a comprehensive 16S rDNA profiling of the dental plaque microbiome of both caries-free and caries-active subjects. Analysis of over 50,000 nearly full-length 16S rDNA clones allowed the identification of 1,372 operational taxonomic units (OTUs) in the dental plaque microbiome. Approximately half of the OTUs were common to both caries-free and caries-active microbiomes and present at similar abundance. The majority of differences in OTU’s reflected very low abundance phylotypes. This survey allowed us to define the population structure of the dental plaque microbiome and to identify the microbial signatures associated with dental health and disease. The deep profiling of dental plaque allowed the identification of 87 phylotypes that are over-represented in either caries-free or caries-active subjects. Among these signatures, those associated with dental health outnumbered those associated with dental caries by nearly two-fold. A comparison of this data to other published studies indicate significant heterogeneity in study outcomes and suggest that novel approaches may be required to further define the signatures of dental caries onset and progression.     

Sorbitol Gum in Xerostomics: The Effects on Dental Plaque pH and Salivary Flow Rates1

Adequate salivary flow is important for patient comfort and maintenance of oral health. Xerostomia, or dry mouth, is a common clinical complaint. Masticatory and gustatory activity can stimulate salivary flow from functional salivary tissue and the use of sugarless mints and gums have been recommended to individuals who complain of xerostomia, but there are minimum clinical data. A clinical study assessing the effect on salivary flow rates and dental plaque pH of a sorbitol-sweetened chewing gum in subjects with the complaint of xerostomia was conducted. The chewing of the gum in this present study stimulated salivary flow in the subjects with xerostomia. Statistically significant stimulated whole mouth and parotid salivary flow rate increases were found when compared to unstimulated whole mouth and parotid salivary flow rates. Chewing of the sorbitol-sweetened gum also effectively reduced the drop in pH seen following the exposure to a fermentable carbohydrate. The findings of this present study indicate that chewing of a sorbitol-sweetened gum may be of benefit to patients with the complaint of xerostomia.     

光学技术在早期龋齿检测中的应用

介绍了光学技术在口腔医学早期龋齿无损检测领域的应用,包括基于牙齿自体荧光效应的定量光导荧光技术和激光龋齿检测技术;基于光散射效应的数字化显影光纤透照术,以及基于牙釉质双折射效应的偏振敏感光学相干断层术和偏振拉曼光谱技术.详细介绍了各种光学方法应用于龋齿检测的基本原理、实验方案和研究现状,并对不同的光学方法进行比较.最后,提出基于频域荧光寿命成像的早期龋齿检测方法,并对该方案的技术路线进行了介绍.     

儿童窝沟封闭联合氟保护漆防龋的效果观察

目的:对儿童窝沟封闭联合氟保护漆的防龋效果进行评价,为儿童龋齿的预防提供干预措施。方法:选择我所预防科于2009年12月～2010年5月检查的3～4岁幼儿120例,按随机数字表法分为观察组和对照组,每组各60例。对照组进行氟保护漆涂布,观察组在此基础上对乳磨牙冠表面点隙沟裂进行窝沟封闭。比较两组6个月、12个月、24个月的龋病发生率及龋均。结果:在6个月时两组龋病发生率及龋均比较,差异均无统计学意义(P>0.05);在12个月时两组龋病发生率比较无显著性差异(P>0.05),观察组龋均显著低于对照组(P<0.05);在24个月时观察组龋病发生率及龋均均显著低于对照组,差异有统计学意义(P<0.05)。结论:相比单一的预防模式,应用窝沟封闭和氟保护漆同时对儿童进行龋病预防干预,能够有效地降低龋病发病率,大大减少龋病对儿童牙齿的破坏,值得临床推广应用。